Year of Publication

2008

Degree Name

Doctor of Philosophy (PhD)

Document Type

Dissertation

College

Arts and Sciences

Department

Psychology

First Advisor

Dr. Michael T. Bardo

Abstract

Previous research has suggested that lobeline, a plant alkaloid derived from Lobelia inflate, has potential to be an efficacious pharmacotherapy for the treatment of methamphetamine dependence. In addition to attenuating methamphetamineinduced dopaminergic alterations in vitro, lobeline has been shown to decrease the primary rewarding effects and discriminative stimulus properties of methamphetamine in rats. It is of clinical interest to assess the utility of lobeline to decrease methamphetamine conditioned cues as these cues have been shown to significantly contribute to relapse.

The current studies assessed the ability of lobeline to block the acquisition and expression of methamphetamine-induced conditioned place preference in rats. Lobeline blocked the acquisition of methamphetamine-induced conditioned place preference when a low dose of methamphetamine was used during conditioning. However, this blockade was surmounted with higher doses of methamphetamine. Furthermore, the expression of methamphetamine-induced conditioned place preference is attenuated following repeated administration, indicating that lobeline not only blocks the primary reinforcing effects of methamphetamine, but it also blocks the environmental cues that become associated with drug administration. These results provide further evidence that lobeline may be an efficacious treatment for methamphetamine dependence.

The rewarding properties of psychostimulants are thought to be mediated, at least in part, by the nucleus accumbens shell. The effects of lobeline on methamphetamine-induced alterations in this dopaminergic region were assessed using microdialysis in rats. Acute lobeline did not have an effect on the methamphetamine-induced increases in dopamine, indicating that repeated lobeline administration may be more efficacious. Interestingly, lobeline potentiated the methamphetamine-induced decrease of the dopamine metabolite, DOPAC. These results suggest that acute lobeline may function to redistribute vesicular dopamine pools within the terminal bouton.

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Psychology Commons

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